Ducting Standard

8/3/2019 Ducting Standard

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SUBURBAN SHEET METAL LTDMailing Address

P.O. Box 739Kennedale, TX 76060

Physical Address528 S. Eden Rd.

Kennedale, TX 76060

Phone (817)478-0801Fax (817)483-6571

Page 1 of 43

Duct Fabrication Specifications

&

Duct Construction


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TABLE 1-1

PRESSURE CLASSIFICATIONFOR DUCTWORKSTATIC

PRESSURE CLASS(INCHES (Pa) W.G.)

+1/2 -1/2 +1 -1 +2 -2 +3 -3 +4 -4 +6 -6 +10 -1

Rectangular Style A A STD STD STV A A A A A A A A A

Round Style STV STD A A A A

Flat Oval Style STD STV A A A

Flexible Style A A STD STD STV A A A A

NOTES FOR TABLE 1-1:

1. STD denotes standard (nonvariable volume) airduct construction requirements (regardless of actualvelocity level) for compliance with this documentfor all cases in which the designer does notdesignate the pressure classification for the ductsystem independent of fan static rating. STVdenotes the standard construction classification forvariable volume ducts for compliance with thisdocument when the designer does not designate aclass for this application.See S1.4 on Page 1-8.

2. A denotes other pressure classes for whichconstruction or installation details are given in thisdocument and are AVAILABLE for designation incontract documents prepared by designers.

3. See Section S1.9 for sealing requirements related toduct pressure class.

4. The pressure class number in Tables 1-1 and 1-1Sdenotes construction suitable for a maximum levelnot less than the maximum operating pressure in

the portion of the system receiving theclassification from the designer.

Text references for ducts:

a) Rectangular...page 1-12b) Round..page 3-2c) Flat oval.page 3-13d) Flexible..page 3-15e) Duct liner...page 2-24

TABLE 1-1S

STATIC PRESSUREDuct Pressure Class Operating Pressure

(in.) (Pa) w.g. 125 Up to w.g.

1 w.g. 250 Over up to 1 w.g.

2 w.g. 500 Over 1 up to 2 w.g.

3 w.g. 750 Over 2 up to 3 w.g.

4 w.g. 1000 Over 3 up to 4 w.g.

6 w.g. 1500 Over 4 up to 6 w.g.

10 w.g. 2500 Over 6 up to 10 w.g.

5. Designer selection of duct construction pressureclass is acknowledgment of acceptable designvelocity level and pressure level including anyoverpressure or underpressure conditions that mayoccur during normal and special modes ofoperation.

6. The designation of a pressure class pertains to

straight duct and duct fittings except for equipmentand special components inserted into the ductworksystems; such items are governed by separatespecifications in the contract documents.


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PRECAUTIONS FOR TABLE 1-1:

1. The construction is, as indicated elsewhere in thismanual, qualified by freedom from structuralfailure; however, accidental overpressure that couldoccur must be provided for at the design stage byoverpressure relief (such as fail sage features,replaceable relief panels, controlled failure points,etc.)

2. Field tests (if ever used) to test structural adequacyshould not exceed 125% of rated pressure. Theassignment of a pressure class number less than

The numerical value of the anticipated operatingpressure involves risk.

3. Leakage test pressure should not exceed ductpressure class level.

4. Short-cycle pressure changes in duct systems cancause temporary noise. This is normally acceptableat system start-up and shutdown. To reduce oreliminate this noise, the designer must specifyshorter-interval bracing, diagonal bracing, lagging,or other control means.


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Duct Sealing Requirements Table 1-2

Seal Class Sealing Required Static PressureConstruction Class

A

All Transverse JointsLongitudinal Seams andDuct Wall Penetrations

4W.G. AND UP

BAll Transverse Joint and

Longitudinal Seams3W.G.

C Transverse Joints 2W.G.

IN ADDITION TO THE ABOVE, ANY VARIABLE AIR VOLUME SYSTEM DUCT OF1W.G. CONSTRUCTION CLASS THAT IS UPSTREAM OF THE VAV BOXES SHALL

ALSO MEET SEAL CLASS C.


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SHEET METAL STANDARDS

DUCT GUAGE AND ENFORCING FOR 1 ESS & DRIVE (+/-)GAUGE OF METAL

DUCT

DIMENSIONS

5

JOINT

4

JOINT

2.5

JOINT

2

JOINT

JOINT

CONSTRUCTION

REINFORCING

0-12 26 26 26 26 FLAT ESSES & DRIVE NONE

13-30 26 26 26 26 1st ESSES & DRIVE NONE



61-72 22 22 22 no Cnt.ref

22 noCnt. ref

TDF NONE

73-96 22 22 22 no Cnt.ref

22 noCnt. Ref

TDF CNT-JNT NONE

97-up 18 18 20 no Cnt.ref

20 noCnt. ref

TDF CNT-JNT 48 MAXSPACING

1 WIDE X 1 HIGH 18GA V-

TYPESTIFFENER

NOTES: 1. TDC DUCT CONSTRUCTED PER SMACNA STANDARDS-FIRST EDITION 19952. DUCT FABRICATED USING SNAPLOCK SEAMS.3. ALL DUCT STIFFENED BY MACHINE FORMED BEADS SPACED AT 12 O.C.4. DUCT WORK TO BE SEALED PER SMACNA HVAC TABLE 1-25. TDC CNT-JNT-CONDU-LOC @ TDC CONNECTOR CENTER OF DUCT & @ TDC CONNECTOR


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DUCT GUAGE AND ENFORCING FOR 1 ESS & DRIVE (+/-) HEAVY GA METALGAUGE OF METAL

DUCT

DIMENSIONS

5

JOINT

4

JOINT

2.5

JOINT

2

JOINT

JOINT

CONSTRUCTION

REINFORCING

0-12 26 26 26 26 FLAT ESSES & DRIVE NONE




61-72 20 20 20 no Cnt.ref

20 noCnt. ref

TDF NONE

73-84 20 20 20 no Cnt.ref

20 noCnt. Ref

TDF NONE


20 noCnt. ref



TYPESTIFFENER

NOTES: 1. TDC DUCT CONSTRUCTED PER SMACNA STANDARDS-FIRST EDITION 19952. DUCT FABRICATED USING PITTSBURG SEAMS.3. ALL DUCT STIFFENED BY MACHINE FORMED BEADS SPACED AT 12 O.C.4. DUCT WORK TO BE SEALED PER SMACNA HVAC TABLE 1-25. TDC CNT-JNT-CONDU-LOC @ TDC CONNECTOR CENTER OF DUCT & @ TDC CONNECTOR


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DUCT GUAGE AND ENFORCING FOR 1 W. G. (+/-) TDFGAUGE OF METAL

DUCT

DIMENSIONS

5

JOINT

4

JOINT

2.5

JOINT

2

JOINT

JOINT

CONSTRUCTION

REINFORCING

0-12 26 26 26 26 HEMMED S & DRIVE NONE

12-36 26 26 26 26 TDF NONE

37-48 24 24 24 26 TDF NONE

49-60 22 22 24 24 TDF NONE

61-72 22 22 22 no Cnt.ref

22 noCnt. ref

TDF CNT-JNT NONE

73-96 22 22 22 no Cnt.ref

22 noCnt. Ref

TDF CNT-JNT NONE


20 noCnt. ref



TYPESTIFFENER



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DUCT GUAGE AND ENFORCING FOR 2 W. G. (+/-)GAUGE OF METAL

DUCT

DIMENSIONS

5

JOINT

4

JOINT

2.5

JOINT

2

JOINT

JOINT

CONSTRUCTIONREINFORCING


13-24 26 26 26 26 TDF NONE

25-30 24 24 26 26 TDF NONE

31-36 22 24 26 26 TDF NONE

37-42 20 24 24 24 TDF NONE

43-48 20 22 24 24 TDF NONE

49-54 22 2224 no

Cnt. ref

24 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

55-60 22 2222 no

Cnt. ref22 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

61-84 22 2222 no

Cnt. ref22 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

85-96 20 2020 no

Cnt. ref20 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

97-up 18 18

18 no

Cnt. ref

18 no

Cnt. ref TDF CNT-JNT

1 WIDE X 1

HIGH 16GA V-TYPE STIFFENER



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DUCT

DIMENSIONS

5

JOINT

4

JOINT

2.5

JOINT

2

JOINT

JOINT

CONSTRUCTION

REINFORCING


13-26 24 24 24 24 TDF NONE

27-30 22 24 24 24 TDF NONE

31-42 20 22 24 24 TDF NONE

43-48 24 2424 no

Cnt. ref24 no

Cnt. refTDF


TYPE STIFFENER

49-60 22 2224 no

Cnt. ref24 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

61-72 22 2222 no

Cnt. ref22 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

73-84 20 2020 no

Cnt. ref20 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

85-96 18 1818 no

Cnt. ref20 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

97-up 18 1818 no

Cnt. ref18 no

Cnt. refTDF CNT-JNT 48 MAX

SPACING


TYPE STIFFENER



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DUCT

DIMENSIONS

5

JOINT

4

JOINT

2.5

JOINT

2

JOINT

JOINT

CONSTRUCTION

REINFORCING


9-22 24 24 24 24 TDF NONE

23-30 22 24 24 24 TDF NONE

31-36 20 22 24 24 TDF NONE

37-42 24 2424 no

Cnt. ref24 no

Cnt. refTDF


TYPE STIFFENER

43-48 22 2222 no

Cnt. ref22 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

49-60 22 2222 no

Cnt. ref22 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

61-72 20 2020 no

Cnt. ref20 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

73-84 18 1818 no

Cnt. ref20 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

85-96

20 2SETS

Cnt. ref

20 2020 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

97-up 18 1818 no

Cnt. ref18 no

Cnt. refTDF CNT-JNT 48 MAX

SPACING


TYPE STIFFENER



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DUCT

DIMENSIONS

5

JOINT

4

JOINT

2.5

JOINT

2

JOINT

JOINT

CONSTRUCTION

REINFORCING


9-12 24 24 24 24 TDF NONE

13-22 22 24 24 24 TDF NONE

23-24 22 22 24 24 TDF NONE

25-28 20 22 24 24 TDF NONE

29-36 24 24

24 no

Cnt. ref

24 no

Cnt. ref TDF

1 WIDE X 1


37-42 22 2222 no

Cnt. ref22 no

Cnt. refTDF


TYPE STIFFENER

43-48 20 2020 no

Cnt. ref20 no

Cnt. refTDF


TYPE STIFFENER

49-60 20 2020 no

Cnt. ref22 no

Cnt. refTDF CNT-JNT


TYPE STIFFENER

61-72 18 1818 no

Cnt.ref20 no

Cnt. ref TDF CNT-JNT

1 WIDE X 1


73-96

18 2SETS

Cnt. ref18 18

20 noCnt. ref



TYPE STIFFENER

97-up

18 2SETSCnt.ref

18 1818 no

Cnt. RefTDF CNT-JNT 48 MAX

SPACING


TYPE STIFFENER



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LONGITUDINAL SEAMS

PITTSBURGH LOCK

BUTTON-PUNCH SNAP-LOCK


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NOTES:


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ELBOW CONSTRUCTION

NOTES:

1. All square elbows will have turning vanes installed.2. All radius elbows will have a throat-radius equal to W.3. Radius elbows will be used anywhere space permits.


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INTERIOR DUCT LINER (SOUND ABSORBERS)

REFERENCE SPECIFICATION SECTION 15895-2.4F


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SINGLE-BLADE VOLUME DAMPER

NOTES:

1. Over 12 High use multiple Blade Dampers.2. Quadrant to be Ventfabric No. 635.


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2 ROLL-FORMED AIR TURNING VANES

Turning Vanes are non-adjustable 90 air turnsdesigned to reduce the pressure loss in squareduct elbows. The galvanized steel blades aredouble walled and formed to assure that anypoint on one blade is equidistant from thesame point on an adjacent blade. This preciseblade shape maintains constant duct area and

assures constant air velocity around the ell,eliminates loss due to velocity changes andresults in low friction loss. The blade is rigidand eliminates the need for cross bracing orreinforcing rods. Roll-formed from coils ofsheet metal, surfaces and edges are smoothand free from edge friction and bladeturbulence. Blades assemble over precision-formed tenons on the runners, which insuresprecise blade alignment, and proper spacing,and predictable engineering performance. Thecomplete unit is screwed or riveted into theduct ell.

NOTE-TURNING VANES WILL BE TACK-WELDED TORUNNERS FOR H.P. APPLICATIONS

DUCT VELOCITY IN FPMTYPE OFELL 500 1000 1500 2000 2500 3000

DUCTURNS .01 .02 .04 .07 .11 .16

NO VANES .02 .08 .19 .35 .52 .75


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SINGLE-BLADE VOLUME DAMPER


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18 GA WELDED STAINLESS STEEL DISHWASHER EXHAUST DUCT

ALL SEAMS, JOINTS, ANDPENETRATIONS TO HAVECONTINUOUS EXTERNALWELDS. (TYPICAL)

REFERENCE SPECIFICATION SECTION 15890


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16 GA WELDED BLACK IRON KITCHEN EXHAUST DUCT


REFERENCE SPECIFICATION SECTION 15872


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16 GA WELDED STAINLESS STEEL KITCHEN & DISHWASHER DUCT



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FLEXIBLE CONNECTIONS

VENTGLAS

VENTGLAS is a heavy glass fabric, double coated with Neoprene. The fabric is non-combustible,and the coating fire-retardant. The fabric is absolutely waterproof and air-tight, and resistant to moreacids, alkalis and to gasoline and grease.

RECOMMENDED USES - VENTGLAS, because it is water-proof and air-tight, can be used inhigh pressure systems, and because of its resistance to most acids, alkalis, gasoline and grease, onfume hoods. In fact, it can be used satisfactorily in practically every type of installation except oninduced draft fans and in connections exposed to the weather.

APPROVALS Classified by UNDERWRITERS LABORATORIES, INC. as to flammability only.(Under new procedures adopted by UL, effective January 1972, products included in the BuildingMaterials List are classified rather than listed to prevent erroneous impressions concerningcharacteristics of products or nature of tests conducted on them.) Registered with California State FireMarshall. Approved by the City of Denver. Conforms with National Fire Protection AssociationPamphlet 90A (1968), Paragraph 304, outlining standards for vibration isolation connectors in ductsystems.

SPECIFICATIONS Weight: Approximately 30 ounces per square yard. Strength: 540 pounds persquare inch in the warp, 440 pounds per inch in the filling. Fire-Resistance: Basic fabric non-

combustible, coating five-retardant. Complies with UNDERWRITERS LABORATORIES Standard#214. Heat-Resistance: Will withstand 300 F, for short periods, 250F, continuously. WaterproofQualities: Will support a column of water 4 in diameter and 48 high for 10 minutes with noleakage. Mildew-Resistance: Neoprene is not affected by mildew. Chemical-Resistance: Is resistanceto most acids and alkalis, and to gasoline, oil, and grease.


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Labor Saving Tie Rod Construction Hardware

New STUD-LOCK

New STUD-LOCKis the result of combining our field testedand a threaded stud. The one piece

component will allow one person to reinforce duct withoutassistance. Once STUD-LOCK is driven in, the threadedstud extended out of each of conduit, will allow the installer toeasily find pre-drilled holes in both insulated and non-insulated duct.

Once in place,STUD-LOCKkeepsthe conduit in place

for fastening thesealed washer andlocknut outside theduct wall.

SOLD IN SETSTO ORDER CALL

1-800-231-8040 FAX 301-475-1665E-mail: [email protected]


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Dyn-O-Seal IIIndoor/Outdoor water based duct sealant

_________________________________________________________________________________________________

Dyn-O-Seal II is an all purpose industrial grade duct sealant for all types of metal duct, glassfiber duct board, and flex duct, as well as duct fabric and flexible tubing runouts. Dyn-O-Seal IIincludes UV inhibitors for extended outdoor exposure and built-in fiber reinforcement forexceptional strength. This non-toxic water based product is solvent free and is suitable forresidential use.

INDUSTRIAL GRADE USE

INDOOR/OUTDOOR

FIBERREINFORCEMENT

NON SAGFORMULATION

PROVEN RELIABILITY

SUITABLE FOR RESIDENTIAL USE

TECHNICAL DATAColor GrayConsistency .. Smooth creamy textureBase ........... Fiber reinforced resinsSolvent Water Based

Weight per Gallon 10.4 lbs.Solids Content .. 64%Viscosity . ThixotropicCoverage (per gal) Up to 320 lin. ft. at 3

width 20 mil thickness.Shore A Hardness . >20Flexibility . Passes inch mandrel bendTime to Test 48 hours*Service Temperature -20F to 200F (-20C to 94C)Weather Resistance . Weather resistantMildew Resistance Mold & Mildew ResistanceVOC .. < 20 GPLPressure Classes .. SMACNA , 1, 2, 3, 4, 6 and

10 inches w.g.Seal Classes ... SMACNA A, B, CPackaging 1/12 US gal. cartridge

1 US gal. pail (3.78 Ltr.),2 US gal. pail (7.56 Ltr.),5 US gal. pail (18.9 Ltr.)

Freeze/Throw Stability . Passes 5 CyclesSpecifications

Compliance Passes ASTM C731,ASTM C732, ASTM 02202

* May vary according to temperature and functionality

APPLICATION

Apply to outer surface of duct joint only

Temperature 35F to 110F (12C to 44C)Method .. Brush, putty knife, caulk gun,

PumpPreparation .. Surface must be dry, dirt, oil,

and grease free.Rate Apply at joints and fasteners to

20 mil thick wet film after ductwork is installed

Clean Up Wet ... Soap and waterClean Up Dry CG-658 or Solvent. (Use safe

Handling practices.)

Painting . Only latex or epoxy paints

STORAGETemperature 35F to 110F (12C to 44C)Shelf Life .. One year (unopened)Flammability Non-flammable


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Carlisle Coatings &DynAir Inc. Waterproofing Incorporated2100 Rememberance P.O. Box 1239Lachine (Quebec) H8S 1X3 Wylie, Texas 75098Phone: (514) 639-1616 Phone: (800) 527-7092

Printed in U.S.A. 02/01 supercedes 07/00 The Carlisle Corportation Fax: (514) 639-5252 Fax: (800) 285-7430

PRECAUTIONSSurface must be clean and free of moisture, contamination and

foreign matter. Do not allow this product to freeze. Do not applythis when rain or freezing temperatures will occur within 36hours. Do not apply this product where temperatures willexceed 200F. Keep out of the reach of children. Review MSDSfor complete safety information prior to use. DO NOT use whereacidic or alkaline chemicals are present (ie. lab fume hood,vents, etc.)

For Industrial Professional Use Only.


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ROUND, OVAL, AND FLEXIBLE DUCT

3.1 ROUND DUCT CONSTRUCTION STANDARDS

Fitting classes available for designer use in project specificationsor contractor selection as being fit for the project specificationsthat adopt these standards are as follows. Category listings arenot intended to preclude different selections for fittings thatfunction as area change, direction change, converging flow,diverging flow, or special purpose. Category listings also do notnecessarily apply to their end connections to other fittings, straightduct sections or equipment.

1. All continuously welded or brazed.2. Tack or spot welded (and sealed or unsealed).3. Seam locked (and sealed or unsealed).4. Rivet, screw, or punched-die-stamp locked (and sealed or

unsealed).

The preceding categories may have additional formingprescriptions such as rolled, stamped, gored, spun, pleated, semi-pleated, or other methods. For purposes of distinction, openingsin sections of straight ducts to receive taps of any connectionmethod are not deemed to be fittings; but connection thereto maybe specified by a prescribed method.

S3.0 Round ducts shall be constructed in accordance with Tables3.2 and 3-3. Table 3-2 is based on G-60 coated galvanized steelof ASTM Standards A653 and A924 grades. Uncoated, polyvinylcoated, aluminum alloy coated or aluminum-zinc alloy coatedsteel or stainless steel may be used if a minimum correspondingbase metal thickness and material strength is provided.Lockforming quality is required. The use of an alternative materialrequires specification or approval by a designer.

S3.1 Fittings shall have a wall thickness not less than thatspecified for longitudinal-seam straight duct in Table 3-2 and 3-3.The diameter of fittings shall be appropriated for mating withsections of the straight duct, equipment, and air terminals to whichthey connect.

S3.2 Sleeves, collars, and fittings to connect a round duct to arectangular duct or to flexible ducts shall conform to S3.1 unless adifferent practice is supported by test data or affidavits confirmingsuitability for the service.

S3.3 Nothing in this specification is meant to imply that thedesigner cannot by project specification designate acceptableconstruction methods.

S3.4 The use of a saddle or a direct connection of a branch into alarger duct is acceptable. Where they are used, the diameter ofthe branch shall not exceed two-thirds of the diameter of the mainand protrusions into the interior of the main, are not allowed.

Direct connection of a branch into a main shall include mechanicalattachments sufficient to maintain the integrity of the assembly.All saddle fittings shall be sealed at all pressures.

S3.5 Where other limitations are not stated, mitered elbows shallbe based on the velocity of slow and shall be constructed tocomply with Table 3-1.

S3.6 The illustration of 90 elbows in Figure 3-3 does not precludeshapes of less than 90 degrees.

S3.8 Volume damper construction is provided on page16.

S3.10 The requirements of Table 1-2 for sealing are applicable.

TABLE 3-1 MITERED ELBOWS

R/D RatioNumber ofMitered Pieces

Duct Velocity Centerline Radius to Duct Diameter 90 deg. 60 deg. 45 deg.Up to 1000 fpm 0.6 3 2 2

1001 to 1500 fpm 1.0 4 3 2Above 1500 fpm 1.5 5 4 3


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3.2 COMMENTARY

Round duct has a high strength to weight ratio, uses the leastmaterialTo convey air at a given friction loss, and is comparatively easy toseal. The wall thickness suitable for positive pressure applicationis generally less than that for negative pressure. For positivepressure (and low negative pressure), girth ring reinforcement isnot necessary. However, rings may be used to maintain theround shape to facilitate handling, shipment, or connection.

The tables indicate that a 10 W.G. (2500 Pa) negative pressure isthe maximum classification. Some of the constructions in thetables will qualify at higher negative levels. For spiral ducts,higher negative pressure service information (and burstingpressure in positive mode) is available from industry sources.

Designers should consult SMACNAs Round Industrial DuctConstructionmanual for:

a) construction of any system carrying particulate orcorrosive fumes (i.e., systems for other than clean air),

b) use of high negative pressure construction or(conservatively) for higher positive pressure than thisdocument provides for,

c) extended hanger spacing,d) engineering design of bolted flanged joints,e) negative pressure construction alternatives, andf) negative pressure service levels over 10: W.G. (2500 Pa)

This manual also does not indicate preference for any one type oflongitudinal seam. The length of straight longitudinal seam ductwill generally be determined by the size of the fabricators rollingequipment. The length in Table 3-2 and 3-3. The diameter offittings shall be appropriated for mating with sections of thestraight duct, equipment, and air terminals to which they connect.Of spiral seam duct is limited by considerations such as in-linefitting frequency, potential for damage in shipment,maneuverability of the sections on the job, the number of supportpoints needed to place the duct in its final location, and otherfactors.

The most popular transverse joints are the slip or lap types. Theflanged joint is used in ducts over 60 (1524 mm) in diameterbecause of its advantage in retaining the circular shape.

Access to joints for makeup and orientation in vertical orhorizontal positions will influence the choice of connection.

The SMACNA HVAC Duct System Designmanual and theASHRAE Fundamentals Handbookchapter on duct designcontain far more configurations of round fittings than this manual.Friction loss data is provided in these design manuals. Wherefittings of comparable or better performance are illustrated in ductdesign handbooks, designers are encouraged to consider allowinga substitution. Omissions from this document are not intended as

prohibitions against using other constructions.

Double-wall rigid round duct is available from several industrysources. It is used for its acoustical value, and the perforated(typically metal) inner wall provides resistance to erosion of theduct liner.

Round spiral seam ducts with thinner than traditional wallthickness and with one or more corrugations (ribs) formedbetween the lock seams have been introduced in industry. Someof these forms have been tested for compliance with UL Standard181 and have qualified for Class) listing. As the industry developsmore experience with these in installation and service, and asmore functional performance criteria are identified, it is anticipatedthat such forms will be added to SMACNA construction standards.Authorities and contractors are invited to evaluate them byinformation currently available.

Precautions: Small differences occur in the diameter of ductsand fittings. Proper clearances are necessary. Verify suitability offit, particularly when procurement is from outside sources.


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TABLE 3-2A

ROUND DUCT GAGE UNREINFORCEDPOSITIVE PRESSURE

+2 w.g. +4 w.g. +10 w.g.MAX. DIA.

Spiral Seam Long. Seam Spiral Seam Long. Seam Spiral Seam Long. Seam

6 28 28 28 28 28 28

8 28 28 28 28 28 26

10 28 26 28 26 28 26

12 28 26 28 26 26 24

14 28 26 26 24 26 24

16 26 24 26 24 24 22

18 26 24 24 24 24 22

19-26 26 24 24 22 24 22

27-36 24 22 22 20 22 20

37-50 22 20 20 20 20 20

51-60 20 18 18 18 18 18

61-84 18 16 18 16 18 16


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TABLE 3-2BROUND DUCT GAGE

NEGATIVE PRESSURE-2 w.g. -4 w.g. -10 w.g.

MAX. DIA.Spiral Seam Long. Seam Spiral Seam Long. Seam Spiral Seam Long. Seam

6 28 28 28 28 28 28

7 28 28 28 28 26 26

8 28 28 28 28 28 26

9 28 28 28 26 26 24

10 28 26 28 26 28 26

11 28 26 26 24 26 22

12 28 26 28 26 26 24

13 28 26 26 24 24 20

14 28 26 26 24 26 24

15 28 24 24 22 22 20

16 26 24 26 24 24 22

17 26 24 24 20 22 18

18 26 24 24 24 24 22

19 24 22 24 20 22 18

20 24 22 22 20 22 18

21 24 20 22 18 22 18

22 24 20 22 18 22 18

23 24 20 22 18 20 16

24 22 20 22 18 20 16

25-26 22 20 20 18 20 18 A4

27-29 22 18 20 16 18 16 A4

30 22 18 20 16 18 16 B4

31-33 20 18 20 16 18 16 B4

34 20 18 20 20 A6 18 16 B4

35-36 20 16 20 20 A6 18 16 B4

37-42 20 16 18 18 B6 18 F12

43-48 20 18 A6 18 18 B6 18 F6

49-60 18 18 B4 18 F6 16 B4 18 F6

61-72 16 18 F6 16 F4

An alphabet letter in the table means that reinforcement angles or their equivalent must be used at the foot interval following the letter.The angle sizes are:

A = 1 x 1 x 1/8; B = 1-1/4 x 1-1/4 x 3/16; C = 1-1/2 x 1-1/2 x 3/16; D = 1-1/2 x 1-12 x 1-1/4; E = 2 x 2 x 3/16; F = 2 x2 x 1/4

If companion flange joints are used as reinforcements, those for 25 to 36 diameter shall be 1-1/2 x 1-1/2 x3/16; for 37 to 48diameter 2 x 2 x 3/16; for 40 to 60 diameter 2-1/2 x 2-1/2 x 3/16; for 61 to 72 diameter 3 x 3 x .


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TABLE 3-3

ALUMINUM ROUND DUCT GAGE SHCEDULEMaximum 2 w.g. Static Positive Maximum 2 w.g. Static Negative

Duct Diameter inInches

Spiral Seam GageLongitudinal Seam

GageSpiral Seam Gage

Longitudinal SeamGage

3 thru 8 .025 .032 .025 .040

9 thru 14 .025 .032 .032 .040

15 thru 26 .032 .040 .040 .050

27 thru 36 .040 .050 .050 .063

37 thru 50 .050 .063 .063 .071

51 thru 60 .063 .071 N.A. .090

61 thru 84 N.A. .090 N.A. N.A.

NOTES:

Construction of aluminum duct and fittings shall otherwise correspond in the same relationship as for steel duct.

Sheet material shall be alloy 3003-H14 unless otherwise specified. Aluminum fasteners shall be used. Structural members (if used)shall be alloy 6061-T6 or galvanized steel. Hangers in contact with the duct shall be galvanized steel or aluminum.

N.A. means not readily available or not assigned.


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SEAMS ROUND DUCT AND FITTINGS FIG. 3-1


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TRANSVERSE JOINTS ROUND DUCT FIG. 3-2


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ROUND DUCT ELBOWS FIG. 3-3


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90 TEES AND LATERALS FIG. 3-4


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CONICAL TEES FIG. 3-5

Date post:	07-Apr-2018
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Ducting Standard

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